Can we use resistor attenuator

[Chuck H]

How did this turn into a "how to make an attenuator" thread???

As far as an actual reactive load, ie: one that moves mechanically but doesn't make sound, why not use an electric motor with a spring load on the shaft? The Weber speaker motor is just an inductor. It ceases being a motor when it fails to drive anything. An electric motor with a dual opposing spring load should work though. Not sure if they can be had in the correct impedance though.

Chuck

[Steve Conner]

How did this turn into a "how to make an attenuator" thread???

As far as an actual reactive load, ie: one that moves mechanically but doesn't make sound, why not use an electric motor with a spring load on the shaft? The Weber speaker motor is just an inductor.

No, as I understand it, that's what the MASS is, a motor with a spring load on the shaft. The voice coil can still move around, there's just no cone on it.

In any case, the spring load together with the motor's inertia transforms into a parallel resonant LCR circuit in the electrical domain. So you can use a honking great inductor and capacitor, resonating together at 70, 90, whatever Hz, to get exactly the same result as the MASS. Weber just figured out that it's cheaper to use the motor off a speaker.

Servodrive make a subwoofer where the cone is driven by a permanent magnet DC motor with a crank, like the piston in an engine. You connect the motor armature straight to a power amp as if it was a regular woofer.

[888guitars]

The servo drive is huge. and it is really only efficient at really low freq. Not sure if it could be tuned up with a crossover network? I have used the servodrive speakers (subs) at a festival I was working sound for, I tried to tune the system and when I grabbed the crossover point the subs would just disappear above 100hz.

[tubeswell]

Well, your government should take China very seriously.
To them it is not the Far East but the Uncomfortably Close North.

UR darn tootin'. They sent their top military man here just yesterday to spy on our military bases and report back with invasion plans

Top Chinese official visits - politics - national | Stuff.co.nz

(What ah didn't git wus our top military man just shook his hand and showed him everything )

[jmaf]

I read book about THD hot plat, It said Hot plat is a purely resistive attenuator, with some passive LC frequency shaping to compensate for the perceived loss in bass and treble as the attenuation is increased.
I think we can use purely resistive attenuator and EQ in amp, Because EQ in smaller signal easy and lower cost, when we use EQ in attenuator, It is very expensive because we have to use high voltage and current LC components.
It will high cost of all gear.

C'mon guys, give KLD a break. I'll go ahead and help him.

KLD, the most impressive attenuator I've seen was at the Fiktitius Fair in the Netherlands. It worked like this:

A 100 Watt amp is hooked up to a monstro-power LED. A tiny LDR is placed at 1 meter from it and picks up the AF modulated light. The LDR is of course incapable of anything so you've got a 0.001 Watt copy of the 100 Watt signal which is of course a 100 dB attenuation level, something unseen.

I've seen one using a fan too. A ceiling fan would be hooked up to the output of the amplifier and a windemodulator would pick up the variations in air pressure, sort of like a speaker but with more sensibility. The windemodulator would produce something like 80 dB attenuation, also something unseen.

Both of these projects are unseen actually. Hope this helps.